chore: Java 8 unit test to build code in Java 17 and run tests on Java 8 (#1800) (#2332)

* Our Java projects are configured to produce Java 8-compatible bytecode via https://togithub.com/googleapis/java-shared-config/blob/main/pom.xml#L848. This unit test change ensures this config is applied correctly.

* This change also switches the JDK distribution of GitHub Actions to temurin from zulu.

* For the repositories that mark "dependencies (8)" and "dependencies (11)" as required, they should point to only "dependencies (17)" via `.github/sync-repo-settings.yaml` and repo's Settings tab.
Source-Link: https://togithub.com/googleapis/synthtool/commit/cbe010084fc59dc15730c86e9b8e03ddac1de050
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-java:latest@sha256:32851debfefed2b66038e0141f1b5c2103bb59ba80b7475adbc10ef7abab3de7

Author: gcf-owl-bot[bot]

.github/.OwlBot.lock.yaml

@@ -13,4 +13,5 @@
 # limitations under the License.
 docker:
   image: gcr.io/cloud-devrel-public-resources/owlbot-java:latest
-  digest: sha256:ad9cabee4c022f1aab04a71332369e0c23841062124818a4490f73337f790337
+  digest: sha256:32851debfefed2b66038e0141f1b5c2103bb59ba80b7475adbc10ef7abab3de7
+# created: 2023-06-22T15:06:52.039318836Z

.github/dependabot.yml

@@ -5,10 +5,15 @@ updates:
     schedule:
       interval: "daily"
     # Disable version updates for Maven dependencies
-    open-pull-requests-limit: 0
+    # we use renovate-bot as well as shared-dependencies BOM to update maven dependencies.
+    ignore:
+      - dependency-name: "*"
   - package-ecosystem: "pip"
     directory: "/"
     schedule:
       interval: "daily"
     # Disable version updates for pip dependencies
-    open-pull-requests-limit: 0
+    # If a security vulnerability comes in, we will be notified about 
+    # it via template in the synthtool repository.
+    ignore:
+      - dependency-name: "*"

.kokoro/build.sh

@@ -47,7 +47,8 @@ set +e
 
 case ${JOB_TYPE} in
 test)
-    mvn test -B -ntp -Dclirr.skip=true -Denforcer.skip=true
+    echo "SUREFIRE_JVM_OPT: ${SUREFIRE_JVM_OPT}"
+    mvn test -B -ntp -Dclirr.skip=true -Denforcer.skip=true ${SUREFIRE_JVM_OPT}
     RETURN_CODE=$?
     ;;
 lint)